Systems and methods for synchronizing between an in-vivo device and a localization system

ABSTRACT

An in-vivo device may allocate a sensing window in a work cycle for sensing and processing localization signals to determine the location/orientation of the in-vivo device. The in-vivo device may use a timing unit to schedule transmission of data frames and the sensing of the localization signals relative to a reference time embedded in work cycles. The timing unit may produce a clock signal based on which the in-vivo device may measure time specifics, which define the sensing window, relative to the reference time. A receiver may use data embedded in data frames to restore the clock signal and the reference time, and, from them, and using identical or similar time specifics, generate a synchronization signal for a localization signals source (LSS) to enable the LSS to generate localization signals in synchronization with the sensing windows.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of PCT InternationalApplication No. PCT/IL/2012/050096, International Filing Date Mar. 18,2012, entitled Systems and Methods for Synchronizing between an In-VivoDevice and a Localization System, published on Sep. 27, 2012 asInternational Publication Number WO 2012/127469 claiming priority ofclaiming priority of U.S. Provisional Patent Application No. 61/466,145,filed Mar. 22, 2011, which are incorporated herein by reference in itsentirety.

FIELD OF THE INVENTION

The present invention generally relates to an in-vivo system and morespecifically to a synchronization method for synchronizing between anin-vivo device and an in-vivo device localizing system, and to anin-vivo system and localization signal system using the synchronizationmethod.

BACKGROUND

In-vivo measuring systems are known in the art. Some in-vivodevices/systems that traverse the gastrointestinal (GI) system mayinclude one or more imaging sensors, for imaging (e.g., capturing imagesof) the interior of the GI system, and/or sensors of other types.In-vivo devices may traverse the GI system by being pushed through theGI system by peristaltic force exerted by the digestive system, or bybeing maneuvered (e.g., magnetically). Some applications require knowingthe current location and/or current orientation of the involved in-vivodevice. For example, in order to magnetically maneuver an in-vivodevice, for example in the GI system, the magnetic maneuvering systemhas to know the current location/orientation (and the targetlocation/orientation) of the in-vivo device in order to generate thecorrect steering magnetic fields.

Conventional localization systems use various techniques to detect thelocation and/or orientation of in-vivo devices. In some systems, thein-vivo device includes a magnet for producing a constant magnetic fieldthat is sensed outside the in-vivo device. For example, U.S. Pat. No.7,392,808 discloses a system for detecting the location of an in-vivodevice that includes a magnetic field generator that generates aconstant magnetic field that is sensed by external magnetic fielddetectors. Due to the limited space in in-vivo devices, inclusion of amagnet in them is undesirable.

In other localization systems, such as in the system disclosed in U.S.Patent application number 2009/0018434, the in-vivo device includes aresonant circuit. Measuring the influence of the resonant circuit on anexternal magnetic field enables to locate the in-vivo device. Suchsystems, which typically use an external magnetic field generator and anexternal magnetic field detector, require that the patient whose GIsystem is monitored be positioned at a certain location in-between themagnetic field generator and the external magnetic field detector.

In other localization systems the in-vivo device contains magnetic fieldsensing coils, and the external magnetic field generator generates analternating magnetic field continuously, which is undesirable forvarious reasons. One reason is that a constant alternating magneticfield may interfere with other functions of the device. Another reasonis that the in-vivo device has to continuously allocate resources toprocess the signals induced in the magnetic sensing coils, rather thanbeing able to use these resources for other tasks as well.

Advanced maneuvering systems use alternating current (“AC”) magneticfields and direct current (“DC”) magnetic fields to maneuver devices invivo. However, an advanced maneuvering system and a conventionallocalization system cannot coexist, for example, because the externalmaneuvering AC magnetic field may have a negative side effect on thereadout of the localization sensing coil of the in-vivo device, and theexternal AC localization signal may have a negative side effect on themaneuvering force that maneuvers the in-vivo device. If an in-vivodevice includes a ‘localization’ magnet (as opposed to a ‘maneuverable’magnet), for example as per the localization system disclosed in U.S.Pat. No. 7,392,808, the external maneuvering DC magnetic field may applyan undesired maneuvering force on the in-vivo device's localizationmagnet. If an in-vivo device includes an LC circuit, for example as perthe localization system disclosed in US 2009/0018434, localizing andmaneuvering the in-vivo device may suffer from at least some of theaforesaid deficiencies.

For at least the reasons set forth above, conventional localizationsystems impede usage of advanced maneuvering systems. Therefore, itwould be beneficial to have a method that would enable a magneticmaneuvering system to steer an in-vivo device and a magneticlocalization system to locate the in-vivo device without the two systemsinterfering with one another. In addition, since an in-vivo devicetypically performs various tasks (e.g., imaging the GI system,processing various types of data, storing/retrieving data in/from itsmemory, transmitting sensory data, receiving commands, etc.) that aretimed internally, it would also be beneficial to synchronize betweentransmission of localization signals by a localization system andsensing of these signals by the in-vivo device.

SUMMARY

An electromagnetic field sensing time window (“sensing window” forshort) may be allocated in a work cycle of the in-vivo device forsensing electromagnetic localization signals, and for processing thesensed signals. The in-vivo device may operate according to the workcycle. A “work cycle” may be a cycle or repeated time period, dividedinto time slots or periods, that includes a transmission period duringwhich the in-vivo device transmits data (e.g., data frame; e.g., imageframe), for example to a data recorder, via a first communicationchannel, and an idle period during which the in-vivo device does nottransmit data via the first communication channel (but it may transmitdata via a second communication channel or be occupied executinginternal tasks). Time specifics (e.g., start time, duration, terminationtime) that may define the sensing window may be defined such that thesensing window is wide enough (e.g., encompass a long enough timeperiod) to enable the in-vivo device to sense as many localizationsignals as required to determine the location and/or orientation of thein-vivo device, and narrow enough and located in the work cycle suchthat it would not interfere with other activities that the in-vivodevice may be involved in. The sensing window may be divided to, orinclude, n (n=1, 2, 3, . . . ,) sensing sub-windows to enable thein-vivo device to sense, for example, n localization signals during eachsensing window, and additional time specifics may include timeinformation related to the sensing sub-windows as well. In oneembodiment, n=3 to enable the in-vivo device to sense three localizationsignals that may be associated, for example, with an X,Y,Z coordinatessystem. One or more sensing sub-windows may additionally be used tosense orientation signals for determining the spatial orientation of thein-vivo device. “Localization signal” and “orientation signal” arehereinafter collectively referred to herein as “localization signal” and“sensing signal”. Each particular localization signal may be sensedduring a particular sensing sub-window which the in-vivo device mayallocate/reserve for it.

In one embodiment, the sensing window may reside, be within the timeperiod defined by, or may occur, in idle periods. In another embodiment,the sensing window may reside in transmission periods. In oneembodiment, the in-vivo device may transmit localization data thatrepresent sensed electromagnetic signals during a transmission period.In another embodiment, the in-vivo device may transmit the localizationdata by using a second (e.g., telemetry) communication channel that isdisassociated from the first communication channel.

The in-vivo device may schedule (e.g., temporally locate) the sensing ofthe localization signals in work cycles (as per the time specificsdefined for the sensing window and/or for the sensing sub-windows) byusing an internal timing mechanism. The in-vivo device may schedule thesensing of the localization signals relative to an internal referencetime whose temporal location in each work cycle may be fixed. The timespecifics defining the sensing window (and the sensing sub-windows, ifthey exist) may be measured relative to the internal reference time,which, in general, may be preset to be at any time point within the workcycles. In one embodiment, the internal reference time may be preset tobe at, or near, the beginning of a transmission period. In anotherembodiment, the internal reference time may be preset to be at, or near,the end of a transmission period. In yet another embodiment, theinternal reference time may be preset to be at a time point within thetransmission period of working cycles. In still another embodiment, theinternal reference time may be preset to be at a time point in the idleperiod of working cycles. The timing mechanism may include a masterclock to produce a (master) clock signal for timing data bits, and basedon the master clock signal the in-vivo device may measure time elapsingfrom the preset reference time, in order to determine when the elapsedtime matches any of the time specifics, and thus when the elapsing timeoverlaps with the sensing window. Time specifics of the sensing windowmay be constant or they may be adjusted or varied, for examplecontingent on a rate at which the in-vivo device transmits data (e.g.,image data).

The data recorder may use, for example, a specific data bit (e.g., databit number 1000 in a data frame) or a group of data bits, or anysuitable signal, that it receives from the in-vivo device to restore orgenerate the in-vivo device's internal reference time. The data recordermay also use, for example, a group or series of data bits it receivesfrom the in-vivo device to restore the in-vivo device's master clocksignal. The data recorder may use the restored reference time and therestored master clock signal, in conjunction with time specifics thatare identical or similar (e.g., adjusted) to the time specifics usedinternally by the in-vivo device to generate a synchronization signalfor a localization signals source (“LSS”). The LSS may use thesynchronization signal to generate localization signals insynchronization with the time specifics defining the sensing windowand/or sensing sub-windows.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments are illustrated in the accompanyingfigures with the intent that these examples not be restrictive. It willbe appreciated that for simplicity and clarity of the illustration,elements shown in the figures referenced below are not necessarily drawnto scale. Also, where considered appropriate, reference numerals may berepeated among the figures to indicate like, corresponding or analogouselements. Of the accompanying figures:

FIG. 1 is a block diagram of a localization system for localizing anin-vivo device according to an example embodiment;

FIG. 2 shows an in-vivo imaging system according to an exampleembodiment;

FIGS. 3A and 3B show sensing windows according to example embodiments;

FIG. 3C shows a timing unit according to an example embodiment;

FIG. 3D shows a timing diagram associated with the timing unit of FIG.3C;

FIG. 4 shows a timing restoration unit according to an exampleembodiment;

FIG. 5 shows a method for synchronizing between an in-vivo device and alocalization signals source according to an example embodiment;

FIG. 6 shows various signals of an in-vivo device according to anexample embodiment;

FIG. 7 shows sensing sub-windows according to an example embodiment;

FIG. 8 shows localization signals and resulting sensed (EMF) signalstimed according to an example embodiment;

FIG. 9 shows example three EMF signals that are simultaneously inducedon a sensing coils assembly (SCA) according to an example embodiment;

FIG. 10 shows an in-vivo device capable of adapting the time specificsof a sensing window according to a frames-per-second (“FPS”) rate usedby the in-vivo device according to an example embodiment;

FIGS. 11A and 11B show timing diagrams associated with the sensingwindow adaptation of the in-vivo device of FIG. 10 according to anexample embodiment;

FIGS. 12A and 12B depict a printed circuit board (“PCB”) of an in-vivodevice that is configured to sense localization signals according to anexample embodiment;

FIGS. 12C and 12D depict the PCB of FIGS. 12A-12B folded/introvertedaccording to an example embodiment;

FIG. 13A shows a cross-sectional view of an in-vivo device according toan example embodiment;

FIG. 13B shows an overall view of the in-vivo device of FIG. 13A;

FIG. 14 illustrates an example magnetic maneuvering system formaneuvering an in-vivo device according to an example embodiment;

FIG. 15 shows a method for timing internal sensing, by an in-vivodevice, of externally generated localization signals according to anexample embodiment;

FIG. 16 shows a method for synchronizing between sensing of localizationsignals by an in-vivo device and generation of the localization signalsby an external localization signals source according to another exampleembodiment; and

FIG. 17 shows a method for synchronizing generation of a localizationsignal to sensing of the localization signal in an in-vivo deviceaccording to another example embodiment.

DETAILED DESCRIPTION

The description that follows provides various details of exemplaryembodiments. However, this description is not intended to limit thescope of the claims but instead to explain various principles of theinvention and the manner of practicing it.

Although embodiments of the invention are not limited in this regard,discussions utilizing terms such as, for example, “processing,”“computing,” “calculating,” “determining,” “inferring”, “deducing”,“establishing”, “analyzing”, “checking”, or the like, may refer tooperation(s) and/or process(es) of a computer, a computing platform, acomputing system, or other electronic computing device, that manipulateand/or transform data represented as physical (e.g., electronic)quantities within the computer's registers and/or memories into otherdata similarly represented as physical quantities within the computer'sregisters and/or memories or other information non-transitory storagemedium that may store instructions to perform operations and/orprocesses. Unless explicitly stated, the method embodiments describedherein are not constrained to a particular order or sequence.Additionally, some of the described method embodiments or elementsthereof can occur or be performed at the same point in time.

In general, an in-vivo device operating with an in-vivo devicelocalization system may be capable, among other things, of: (i)transferring data frames to (and in some embodiments exchanging datawith) the data recorder with which it operates, (ii) sensinglocalization signals (e.g., electromagnetic localization signals) thatare generated by an external system, and (iii) processing thelocalization signals and transmitting consequent localization data tothe data recorder. The localization data transmitted by or from thein-vivo device may represent the raw signal(s) that are induced in thein-vivo device by localization signals, and thus it may have to beprocessed by an external system in order to determine the location ofthe in-vivo device. Alternatively, the raw signals may be processedinternally (by the in-vivo device), and the consequent localization datatransmitted by or from the in-vivo device may represent the location(and/or orientation) of the in-vivo device. The data recorder may becapable, among other things, of: (i) receiving the data frames from thein-vivo device, and (ii) using data frames to generate a synchronizationsignal in order to synchronize between the system generating thelocalization signals and the in-vivo device sensing the localizationsignals.

In one embodiment the system generating the localization signal maytransmit localization signals at specific times and for specific timeperiods which are preset for (and governed by) the in-vivo devicebecause localization signals are to be transmitted to the in-vivo deviceonly during time slots that the in-vivo device allocates or reserves forsensing this type of signals. This type of synchronization helps ensurethat localization signals are transmitted to the in-vivo device onlywhen the in-vivo device is ready to receive and process them. Ingeneral, a time slot (herein referred to as the “sensing window”) may beallocated within each work cycle (e.g., within the transmission periodof each work cycle, or within the idle period of each work cycle) orwithin selected work cycles according to which the in-vivo deviceoperates. The sensing window may be used to sense localization signalsthat originate from an external localization signals source (LSS).

The time specifics (e.g., timing and width or duration) of the sensingwindow and/or the time specifics of sensing sub-windows may bepredetermined or chosen in advance after taking into account varioustime constraints of the in-vivo device, such as a need to allocate atime slot for sensing a physical parameter in vivo (e.g., for imagingobjects, sensing pH, etc.), another time slot for receiving instructionsand/or data from an external source, another time slot for processingthe instructions and/or data received from the external source, etc.

A timing mechanism in the in-vivo device, which may predominate thetiming of various processes, tasks, etc. of the in-vivo device, maymeasure time (e.g., by counting clock pulses) in order to identify astart time (Ts) and a termination time (Tt) of the sensing window.During a sensing window the in-vivo device may switch to or enter, andtemporarily remain in, a sensing mode. During the sensing mode thein-vivo device may sense one or more localization signals during, forexample, the respective sensing sub-windows. When the sensing windowelapses, the in-vivo device may exit the sensing mode, for example tocommence or resume other tasks. Assuming a 3-dimensional location of thein-vivo device is determined by using the X,Y,Z coordinates system, alocalization signal associated with the X-axis may be generated by anexternal system and sensed internally by the in-vivo device during asensing sub-window which is allocated for it, and other localizationsignals may likewise be generated and sensed for the Y-axis and for theZ-axis.

The external localization signals source (LSS) that generates thelocalization signals may be subjected to various constraints with regardto the timing of the generation of the localization signals. Forexample, generating the localization signals while the in-vivo device istransmitting data (e.g., image data) may detrimentally affect thetransmission and/or the reception of the data by a receiver (e.g., datarecorder). Therefore, it may be beneficial to generate the localizationsignals while the in-vivo device is not transmitting data. However, asdiscussed above, since during idle periods the in-vivo device may stillbe busy doing other internal activities (e.g., receiving data,processing data), a synchronization signal is transferred to thelocalization signals source (LSS) to thereby indicate to the LSS thesensing window and/or sensing sub-windows that the in-vivo device hasallocated for localization signals. The synchronization signal may beproduced externally to the in-vivo device (e.g., by the data recorder)based on the in-vivo device's restored timing mechanism (e.g., restoredor generated reference time and restored master clock signal).Synchronizing between the in-vivo device and the LSS, therefore, meansthat the LSS generates the localization signals during a sensing window(and sensing sub-windows) whose time specifics have been suited to, orgoverned or dictated by, the in-vivo device.

The way the in-vivo device's timing mechanism is restored by the datarecorder (for example) and the way the consequent synchronization signalis used by the LSS are described below. Briefly, clock pulsesoriginating from a master clock of the in-vivo device may be used tocount time units (a time ‘unit’ may equal to, e.g., 1 microsecond)relative to a reference time (e.g., beginning of data transmission fromthe in-vivo device, end of data transmission from the in-vivo device, ora particular data bit in a transmitted data frame, or a particular pulsecount during an idle period, etc.). Any data bit or group of data bits(e.g., prefix data, suffix data, etc.) that is/are contained in a dataframe that is transmitted by the in-vivo device may be used by areceiver (e.g., data recorder) to restore the clock pulses originatingfrom the in-vivo device. The restored clock pulses may be used by thereceiver to count time by using the same time units and relative to thesame reference time. Based on the time counting, the LSS may be caused(e.g., by the data recorder) to start transmitting a localization signalwhen the time count has a first value; e.g., Count1, and terminate thetransmission when the time count has a second value, e.g., Count2 (whereCount2>Count1). (‘Count1’ may designate or represent the start time ofthe pertinent sensing window, and ‘Count2’ may designate or representthe termination time of that sensing window.) The in-vivo device mayenter, transition to, or enable a sensing mode when the time countequals, for example, count value Count1, and exit or disable the sensingmode when the time count equals, for example, count value Count2. Duringthe sensing mode, the in-vivo device may, during the time periods of thesensing window(s), sense and process localization signal(s).

FIG. 1 is a block diagram of a localization system 100 for localizing anin-vivo device according to an example embodiment. Localization system100 may include an in-vivo device 110, a data recorder 120, and alocalization signals source (“LSS”) 130. In-vivo device 110 may beconfigured to sense a physical parameter in vivo. Temperature, pH, andimpedance are example physical parameters. In-vivo device 110 may senseother physical parameters and/or be capable of performing varioussurgical operations in vivo. In-vivo device 110 may capture images(e.g., take pictures) in vivo (e.g., of the GI system). In-vivo device110 may include a transmitter for transmitting data, for example to datarecorder 120, which is related to sensed physical parameter and/orrelated to or represent captured images.

In-vivo device 110 may also include a sensing coils assembly (“SCA”) 112for sensing localization signals generated by an external localizationsystem, for example by localization signals source (LSS) 130. SCA 112may include one electromagnetic sensing coil for sensing anelectromagnetic field, or more than one electromagnetic sensing coilthat may be mutually perpendicular. Each electromagnetic sensing coilmay be used to sense an electromagnetic field in a differentdirection/orientation. For example, one coil may be used to sense anelectromagnetic field in the ‘X’ direction or in the Y-Z plane, anothercoil may be used to sense an electromagnetic field in the ‘Y’ directionor in the X-Z plane, etc. Each localization signal generated bylocalization signals source (LSS) 130 may induce an electromotive force(“EMF”) signal on one or more of the electromagnetic sensing coils ofSCA 112, and the current location, and optionally the currentorientation, of in-vivo device 110 may be determined based on the EMFsignal sensed by the coils of SCA 112. Example electromagnetic sensingcoils are shown in FIGS. 12A through 12D, which are described below.In-vivo device 110 may also include a timing unit 114 for scheduling thetime specifics (e.g., starting time and duration) of the sensing windowduring which SCA 112 may be activated and the EMF signals measured. Anexample timing unit is shown in FIG. 3C, which is described below.

Data recorder 120 may include, among other things (e.g., receiver, dataframe parser, data storage unit, processor, etc.), a timing restorationunit (“TRU”) 122, a synchronization signal unit (“SSU”) 124, and alocalization data unit (“LDU”) 126. Data recorder 120 may include areceiver (not shown in FIG. 1) for receiving data frames 116 fromin-vivo device 110. Data recorder 120 may also include a transmitter fortransmitting commands 118 to in-vivo device 110. Data recorder 120 maytransmit a command to in-vivo device 110, for example, to change a modeof operation (e.g., an image capturing rate of an imager of the in-vivodevice), or to update a parameter of the in-vivo device, etc.

As explained above, a data frame transmitted by in-vivo device 110 andreceived by data recorder 120 may include a data bit or a group of databits that may facilitate generation, reconstruction or restoration, forexample by TRU 122, of the clock pulses and the time referenceoriginating from timing unit 114 and used by in-vivo device 110. TRU 122may use the restored clock pulses and the reference time to find a timeperiod that overlaps or coincides with the time specifics of the sensingwindow(s) used by in-vivo device 110. For example, TRU 122 may countrestored clock pulses relative to a reference time in each or selectedwork cycles of the in-vivo device in order to measure the time elapsing,in the work cycle, from the pertinent reference time. An example timingrestoration unit (TRU) is shown in FIG. 4, which is described below. Ingeneral, any i^(th) data bit in a data frame that is transmitted duringa particular work cycle may be used or serve as a reference time forthat work cycle (e.g., the time of transmission of that bit may be usedas a reference time), and the same i^(th) data bit may be used by boththe in-vivo device and the data recorder as a common reference time. Forexample, it may be predetermined, for example, that the 100^(th) bit ineach data frame (or the time the 100^(th) bit is transmitted) is used asthe reference time during the pertinent work cycle.

Concurrently to the restoration of the in-vivo device's clock signal andreference time by the timing restoration unit (TRU) 122, synchronizationsignal unit (SSU) 124 may produce a synchronization signal 128 thatcomplies with the time specifics of the sensing window(s), and maytransfer synchronization signal 128 to localization signals source (LSS)130, for example via a communication cable or wirelessly.Synchronization signal 128 enables LSS 130 to correctly time thegeneration or creation of one or more localization signals (in the formof electromagnetic field(s)). For example, LSS 130 may generate anelectromagnetic field 132 at a time and for a duration set forth by, orcomplying with, synchronization signal 128, and therefore, in compliancewith the restored sensing window(s), and therefore in compliance withthe sensing window(s) originally used by in-vivo device 110. Since thesensing window(s), which may be used by in-vivo device 110 during eachor selected work cycles, and the restored sensing window(s) used by datarecorder 120 temporally match (within an acceptable margin), LSS 130generates and transmits localization signal 132 exactly in the timeslot(s) during which in-vivo device 110 uses sensing coils assembly(SCA) 112 to sense the induced EMF signals and allocates the resourcesrequired for processing the induced EMF signals.

As a result of in-vivo device 110 sensing the induced EMF signals duringa particular work cycle, the in-vivo device 110 may embed datarepresentative of the sensed EMF signals in a data frame that istransmitted (e.g., to a data recorder) during a transmission period, forexample, of a work cycle that follows the particular work cycle. Datathat represent the raw EMF signals, and any variant, manipulation, orderivative of such data (e.g., data representing the actual location ofthe in-vivo device) is referred to herein as “localization data” and“sensing data”. As defined above, “localization data” may also refer todata that is sensed by the in-vivo device and which represents theorientation of the in-vivo device or allows the device to determine theorientation. Alternatively, localization data may be transmitted (e.g.,to a data recorder) not by using the communication channel via whichframes are transmitted, but by using a separate communication channel.Using a separate communication channel to transmit localization data mayenable transmission of large amount of localization data.

Localization data unit (LDU) 126 may include or use a processor andother components and units that are required to interpret, calculate,deduce, infer, or otherwise determine the current position, and,optionally, also the current orientation, of in-vivo device 110 from thelocalization data. After LDU 126 determines the location/orientation ofthe in-vivo device, LDU 126 may transfer corresponding localization data129 to another computing system. Localization data 129 may include datathat represents the current location of in-vivo device 110, or thecurrent orientation of in-vivo device 110, or both location andorientation of in-vivo device 110. The other computing system may, forexample, display the location/orientation data (whether the raw data ora processed version thereof), and/or it may use past and currentlocation/orientation data to display the route traversed by the in-vivodevice and/or a point on a route representative of the GI system, and/orit may use localization data 129 to maneuver, guide or steer in-vivodevice 110.

Localization system 100 may also include a magnetic maneuvering unit(“MMU”) 140 for maneuvering in-vivo device 110, and. LDU 126 maytransfer position/orientation data 129 to MMU 140 in order for MMU 140to use position/orientation data 129 as a feedback to generate amaneuvering magnetic field 142 to guide, steer, or maneuver, in-vivodevice 110 to a new, target or desired location and/or to a new, targetor desired orientation. That is, knowing the current location/positionof in-vivo device 110 (e.g., from location/position data 129), MMU 140may generate an electromagnetic signal 142 to maneuver in-vivo device110 to a required, or target, location or orientation. SCA 112 may bepart of a magnetic steering unit (“MSU”). (An MSU is shown in FIG. 2 at211.) The MSU may include, for example, permanent magnets and Eddycurrent element(s). The permanent magnets and Eddy current element(s) ofthe MSU may interact with electromagnetic signal 142 to produce magneticforces and torques capable of steering the in-vivo device. MMU 140 maycontrol the steering of in-vivo device 110 based, for example, onlocation/orientation signals that are provided by LDU 126 (e.g.,position/orientation data 129). An example MSU is depicted, for example,in FIG. 13A, which is described below.

The operation of MMU 140 may be synchronized to the operation of LSS 130in order to ensure that MMU 140 and LSS 130 do not respectively generatemaneuvering signal 142 and localization signal 132 at the same time.Operation of MMU 140 may be synchronized to the operation of LSS 130also to ensure that MMU 140 generates a position (or orientation)correction signal 142 that is based on up to datelocalization/orientation data. SSU 124 may send a synchronization signal144 to MMU 140 in order to synchronize between MMU 140 and LSS 130.Synchronization signal 144 may be identical to synchronization signal128 or a manipulation or derivative thereof. Synchronization signal 144may cause MMU 140 to generate, for each work cycle of the in-vivodevice, a signal 142 in the form of a short maneuvering signal (a‘maneuvering burst’), or a series of maneuvering bursts, shortly after asensing window is terminated, provided that MMU 140 receives thelocalization data for the sensing window.

FIG. 2 shows an in-vivo imaging system 200 according to an exampleembodiment. While FIG. 1 references an in-vivo device (in-vivo device110) that transmits data frames that may be related to or include anytype of sensory data (e.g., pH data), FIG. 2 shows in-vivo device 110with an imager as an example sensor, in which case in-vivo device 110may be referred to as an “in-vivo imaging device” or an “in-vivoimager”, and frames transmitted by or from in-vivo device 110 may bereferred to as “image frames” (although image frames may include alsoother types of data, including localization data and/or other types ofsensory data). In-vivo imaging system 200 includes in-vivo imager 110,data recorder 120, a user workstation 230, which may be, for example, aworkstation or personal computer, and a display 202 for displaying, forexample, images and/or a video clip or moving image stream which isproduced from images, and for displaying the location and/or orientationof the in-vivo device, etc.

An in-vivo imaging device may have one or more imagers. By way ofexample, in-vivo imager 110 includes one imager (e.g., imager 212)(numbers of imagers other than one or two may be used, with suitablemodifications to the methods discussed herein). In-vivo imager 110 mayalso include a light/illumination source 214 for illuminating a GIsection to be imaged, a frame generator 220 for producing an image framefor captured images, a controller 260, a storage unit 240 for storingdata, a transmitter or transceiver 250 for transmitting images framesand, optionally, for receiving data and/or commands from data recorder120, and an electrical power source 203 for powering these componentsand circuits. Power source 203 may include a charge storing device(e.g., one or more batteries, which may be rechargeable or not) with anelectrical circuit that jointly facilitates transfer of electrical powerfrom an external power source to the in-vivo device throughelectromagnetic induction.

Timing unit 114 may include a timing mechanism (e.g., clock generator)to generate a clock signal to time a work cycle of the in-vivo device.Within the work cycle may be defined a reference time. Transmitter 250may transmit, within the work cycle, a data frame to a receiver (e.g.,data recorder 120). The data frame may contain or include datafacilitating restoration, by the receiver, of the clock signal and thereference time. Storage unit 240 may include a memory for storing timespecifics of (defining) a sensing time window that may be within thework cycle. Controller 260 may be configured, within the work cycle, tomeasure time elapsing from the reference time by using the clock signal,and, based on the elapsed time and time specifics, to operate SCA 112 tosense a localization signal during a time period overlapping with thesensing time window. Controller 260 may also be configured to transmitdata representative of the sensed localization signal during the samework cycle or during a subsequent work cycle.

In-vivo imager 110 may also include a location and steering unit (“LSU”)272. LSU 272 may include sensing coil assembly (SCA) 112 for sensinglocalization signals generated, for example, by LSS 130 of FIG. 1. LSU272 may also include a magnets steering unit (“MSU”) 211 to facilitatemaneuvering of in-vivo imager 110, for example through interaction withmagnetic fields which are generated by a maneuvering system similar tomagnetic maneuvering unit (MMU) 140 of FIG. 1. Data representing orderived from the EMF signals induced in SCA 112 may be transmitted, forexample, to data recorder 120 by embedding the data in image framesand/or by using frames that may be dedicated to transfer of such data.

At the time of, or shortly after, imaging device 110 is swallowed orotherwise inserted, or after some predetermined delay (e.g., 2 minutes),imager 212 may start capturing images of areas of the GI system. Becausenatural light does not enter the intestinal tract, imager 212 does notrequire a light shutter, as opposed to ‘regular’ (i.e., non-swallowable)imagers. The function of the light shutter is, therefore, implemented bythe darkness inside the intestinal tract and by intermittentlyilluminating the field of view (“FOV”) of imager 212. Typically, theexposure time of imager 212 is 2-3 milliseconds. Imager 212 may includean image sensor that may be, or include, an array of photo sensorelements (e.g., pixels) such as 256×256, 320×320, 1 Mega pixel or anyother suitable array. Imager 212 outputs image data 213 by using a pixelformat corresponding to the used pixels. Each image data may represent acaptured image and, optionally, additional selected portions thereof.

Frames generator 220 may receive image data 213 that represents acaptured image, and produce a corresponding image frame (or “frame” forshort) that contains image data 213. A frame typically includes a headerfield that contains information and/or metadata related to the frameitself (e.g., information identifying the frame, the serial number ofthe frame, the time the frame, the bit-wise length of the frame, etc.),and a payload field. The payload may include an uncompressed version ofthe image data and/or a compressed version thereof, and a decimatedimage. The payload may also include additional information, for examplereadout of sensing coils assembly (SCA) 210.

Controller 260 may controllably operate, among other things,illumination/light source 214 to illuminate areas traversed by in-vivoimager 110, and schedule the images capturing times accordingly.Controller 260 may use timing unit 114 to time the operation ofillumination source 214 to illuminate, for example, four times persecond to enable capturing four images per second, and the operation oftransceiver 250 to concurrently transmit corresponding frames at thesame rate or at a different rate. Controller 260 may use timing unit 114to operate illumination source 214 to capture more images per second,for example seventeen images per second, and transceiver 250 toconcurrently transmit corresponding frames at the same rate or at adifferent rate. Controller 260 may temporarily store captured images andrelated image frames in data storage unit 240. Controller 260 may alsoperform various calculations and store interim calculation results indata storage unit 240. Controller 260 may also use timing unit 114 totime the operation of sensing coils assembly (SCA) 112 (to implement thesensing window(s)), and to time the SCA 112 readout from which theposition and/or orientation of in-vivo imager 110 may be deduced (e.g.,by controller 260 or by an external system; e.g., data recorder 120).Controller 260 may also use timing unit 114 to time the writing (e.g.,adding, appending, or otherwise embedding) of corresponding localizationdata (e.g., the sensing coils readout or a manipulated version thereof)into the corresponding frame; e.g., into a frame that is to betransmitted, for example, immediately after the output of the sensingcoils is read. After frames generator 220 produces a frame for acurrently captured image, and embedding localization data into theframe, controller 260 may use transceiver 250 to wirelessly transfer 242the frame to data recorder 120. Data recorder 120 may be worn by theperson whose GI system is to be imaged. Controller 260, by executingsoftware or instructions, may carry out steps which are performed by anyone of timing unit 114 and frame generator 220, and other functions inin-vivo device 110, and thus may function as these units.

In between transmission periods (e.g., within idle periods separatingtransmission periods), controller 260 may use timing unit 114 to operateillumination source 214 to capture an image during a predetermined timewindow within an idle period during which transceiver 250 is dormant,disabled, or inactive, the time window being referred to herein as an“imaging window”. Controller 260 may also use timing unit 114 to operateSCA 112 and to read and process the output of SCA 112 during anotherpredetermined time window within the idle period, the other time windowbeing referred to herein as the “sensing window”. Controller 260 may usetiming unit 114 to time other activities of in-vivo imager 110 (e.g.,receiving commands from data recorder 120, processing and executing thecommands, etc.). Transceiver 250, controller 260, timing unit 114, framegenerator 220, and a controlling part of light source 214 may beembedded within one microchip.

Data recorder 120 may also include a receiver or transceiver 244, aframe parser 270, and a processor 290 for managing them. Data recorder120 may include additional components (e.g., USB interface, SecureDigital (“SD”) card driver/interface, controllers, etc.), elements orunits for communicating with (e.g., transferring data frames, data, etc.to) a processing and/or displaying systems that may be configured toprocess images and localization data originating from in-vivo imager110, and related data.

Transceiver 244 may receive a data frame corresponding to a particularcaptured image, and frame parser 270 may parse the data frame to extractthe various data contained therein (e.g., image data, decimated imageassociated with the particular captured image, localization data, etc.).In some embodiments, some data frames, which are referred to herein as“localization frames”, may be dedicated to contain and transfer only ormostly localization data. Localization frames may, for example, includelocalization data but not image data. Using localization frames inaddition to image frames that include localization data may enablereading the localization data (e.g., the output of the sensing coilsassembly 210) at a rate that is higher than the images capturing rate.For example, n (n=1, 2, 3, . . . ,) localization frames may beinterposed (e.g., ‘inserted’ between, in time sequence), for example,between image frames, to form therewith a stream of frames. TRU 122, SSU124, and LDU 126 are described above in connection with FIG. 1.Processor 290, by executing software or instructions, may carry outsteps which are performed by any one of TRU 122, SSU 124, and LDU 126,and other functions in data recorder 120, and thus may function as theseunits.

User workstation 230 may include a display or be functionally connectedto one or more external displays, for example to display 202.Workstation 230 may receive frames (e.g., image frames, localizationframes, etc.) or images from data recorder 120 and present them inreal-time, for example as live video, or produce a video stream thatalso contains location and orientation information that may also bedisplayed on, for example, display 202. Workstation 230 may include amemory (e.g., memory 204) for storing the frames transferred from datarecorder 120 and possibly related metadata, and a processor (e.g.,processor 205) for processing the stored frames and related data.Workstation 230 may display selected images or a video clip (e.g., amoving image stream) compiled from such images, e.g., to a humanoperator, health care person, physician, etc.

FIG. 3A shows a sensing window 326 according to example embodiment. Anin-vivo device may produce work cycles similar to work cycle 304. Workcycle 304 may include a transmission period 306 during which the in-vivodevice may transmit a data frame, for example, an image frame. Workcycle 304 may also include an idle period 308 during which the in-vivodevice may refrain from transmitting data. The in-vivo device may senselocalization signals during transmission period 306 (sensing window 326is shown partly overlapping transmission period 306). The in-vivo devicemay simultaneously transmit a data frame during transmission period 306and sense localization signals during sensing window 326.

Each work cycle may have associated with it a reference time from orrelative to which time specifics of a sensing window may be measured.The time specifics Tw1 and Tw2 (the onset and termination times,respectively) of sensing window 326 may be measured relative to areference time that resides, occurs, or is within the time perioddefined by in an idle period, for example relative to reference time 322(as shown at 312 and 314, respectively), or relative to a reference timethat resides in or is within the time period defined by a transmissionperiod, for example relative to reference time 324 (as shown at 316 and318, respectively). Sensing windows in other transmission periods may bescheduled (e.g., their time specifics may be measured relative to thepertinent reference time) in the same manner as sensing window 326. Forexample, the time specifics defining sensing window 328 in transmissionperiod 309 may be measured relative to reference time 307.

FIG. 3B shows a sensing window 342 according to another exampleembodiment. An in-vivo device may produce or define work cycles similarto work cycle 304. Work cycle 304 may include a transmission period 306during which the in-vivo device may transmit data, for example, within adata frame. Work cycle 304 may also include an idle period 308 duringwhich the in-vivo device may refrain from transmitting data.

Sensing window 342 is shown partly overlapping idle period 308. The timespecifics Tw3 and Tw4 (the onset and termination times, respectively) ofsensing window 342 may be measured relative to a reference time thatresides in, or is within the time period defined by a transmissionperiod, for example relative to reference time 352 (as shown at 334 and336, respectively), or relative to a reference time that resides in oris within the time period defined by an idle period, for examplerelative to reference time 354 (as shown at 338 and 346, respectively).Sensing windows in other idle periods may be scheduled in the samemanner as sensing window 342. Each work cycle may have associated withit a reference time from or relative to which time specifics of therespective sensing window may be measured.

FIG. 3C shows a block diagram of a timing unit 300 of an in-vivo deviceaccording to an example embodiment. Timing unit 300 may perform orenable performing tasks, activities, operations or processes, asdescribed herein, and some or every activity and/or process performed byor attributed to timing unit 114 may also be performed by or attributedto timing unit 300, and vice versa. Timing unit 300 may include a masterclock generator (“MCG”) 310, a clock counter 320, a reset signalgenerator (“RSG”) 330, a count comparator 340, a memory 350, and asensing window signal (“SWS”) generator 360. By “master clock generator”is meant a pulse generator that generates a clock signal that may becommonly used by the various circuits and components of the in-vivodevice to synchronize their activities, tasks, etc. MCG 310 may be anintegral part of timing unit 300 or external to timing unit 300. Masterclock generator (MCG) 310, which may be, include, or use a free-runningoscillator, may generate a clock signal 311 at a constant frequencyf_(OSC), for example at 8.1 megahertz (MHz). Clock counter 320 maycontinually count the clock pulses generated by MCG 310 to facilitatemeasurement or calculation of an elapsed time.

FIG. 3C will be described further in association with FIG. 3D, whichshows a time diagram related to timing unit 300. The controller of thein-vivo device (e.g., controller 260 of in-vivo device 110) may use MCG310 to time or schedule the various tasks that are executed by thein-vivo device. For example, the in-vivo device's controller, alone orin conjunction with another component/unit of the in-vivo device, mayuse MCG 310 to generate a frame signal F(t) (signal F(t) is shown at 302in FIG. 3C and it is also shown in FIGS. 3A, 3B, and 3D), and use theframe signal F(t) to schedule the transmission of a data frame to occurbetween time t1 and time t2 (i.e., during transmission period 371, whichis the transmission period of work cycle 370), between time t3 and timet4 (i.e., during transmission period 373, which is the transmissionperiod of a work cycle following work cycle 370), etc.

Reset signal generator (RSG) 330 may use the transmission periods 371,373, and so on, and the idle periods 372, etc. of frame signal F(t) toproduce a reset signal R(t) (signal R(t) is shown at 332) that mayinclude a series of reset pulses (e.g., reset pulses 381, 382, 383, and384). RSG 330 may use reset signal R(t), or portion thereof (e.g., onlyR(t) pulses that represent off-to-on transitions in F(t)) to reset clockcounter 320, for example, every time a transmission is (re)commenced(e.g., at times t1 and t3), and/or terminated (e.g., at times t2 andt4). That is, reset signal R(t) may include only one type of resetpulses; e.g., pulses representing only ‘transmission-to-idle’ (i.e.,on-to-off) transitions (e.g., pulses 382, 384, etc.) or pulsesrepresenting only ‘idle-to-transmission’ (i.e., off-to-on) transitions(e.g., pulses 381, 383, etc.). Alternatively, reset signal R(t) mayinclude both types of reset pulses (e.g., pulses, . . . , 381, 382, 383,384, . . . ).

Clock counter 320 may be reset or initialized during each work cycle orduring selected work cycles. Each time RSG 330 resets clock counter 320,which counts pulses of clock signal 311, the value of clock counter 320may be reset, or initialized, to an initial value at a time overlappingwith or coinciding with the reference time. (The initial value of clockcounter 320 may be, for example, zero, or any value that is greater thanzero.) The pulses counting range of clock counter 320 may be utilizedinternally, for example by the in-vivo device's controller, to measure,for example, a time elapsing from a reset pulse of a specific type, forexample, from a reset pulse representing transition from a transmissionperiod to an idle period. Each reset pulse, or selected reset pulses, inreset signal R(t) may indicate a reference time relative to which timespecifics of sensing windows may be measured.

Memory 350 may hold time specifics of a sensing window, such as a firstcount value, N_1, that may be equivalent to or represent the onset timeof the sensing window relative to a reset pulse, and a second countvalue, N_2 (N_2>N_1) that may be equivalent to or represent thetermination time of the sensing window relative to the same reset pulse.For example, if, per timing constraints within idle period 372, asensing window is to ‘open’ or start at time Tw5 and ‘close’ orterminate at time Tw6, the count values N_1 and N_2 may be chosen suchthat they respectively represent times 392 and 394 that elapse from, orrelative to, a designated reset pulse, for example from, or relative to,reset pulse 382. The same count values N_1 and N_2 may likewise bereused for other work cycles.

Count comparator 340 may output a time indication each time the value ofclock counter 320 reaches any of the count values N_1 and N_2, andsensing window signal (SWS) generator 360 may use the time indicationsthat are output by count comparator 340 to produce a correspondingsensing window signal W(t) (signal W(t) is shown at 362). During thesensing window 364, the controller of the in-vivo device (e.g.,controller 260 of in-vivo device 110) may transition to the sensing modeduring which it may enable or activate sensing coils assembly (SCA) 112,read the output of SCA 112, process the output of SCA 112 andtemporarily store corresponding localization data in a memory (e.g., instorage unit 240). The controller of the in-vivo device may embed thelocalization data obtained during a particular work cycle, for example,in the next data frame that is scheduled to be transmitted. For example,the controller of the in-vivo device may embed localization data that isobtained during idle period 372 in a data frame that is scheduled to betransmitted during transmission period 373, or in a data frame that isscheduled to be transmitted during a transmission period of some otherwork cycle. The embodiment shown in FIG. 3B (i.e., sensing windows thatreside in or is within the time period defined by idle periods) isfurther elaborated below, for example, in connection with FIG. 6, FIG.7, FIG. 8, and FIGS. 11A-11B, and similar principles, which aredescribed in connection or in association with these figures, maylikewise be applicable to the embodiment shown in FIG. 3A.

FIG. 4 shows a block diagram of a timing restoration unit (“TRU”) 400according to an example embodiment. Timing restoration unit (TRU) 400may include a master clock and a reset signal restoration (“MCRR”) unit410, a pulse counter 440, a count comparator 450, a memory 460, and asensing window signal (SWS) generator 470. MCRR unit 410 may include aclock restoration module (“CRM”) 420 and an end-of-transmission (“EOT”)detector 430. A data recorder (e.g., data recorder 120) may receive adata frame 402 from an in-vivo device, and data frame 402 may includesuffix data bits.

As explained in connection with timing restoration unit (TRU) 122,suffix data of a data frame may be used to indicate theend-of-transmission (EOT) time of the data frame. In addition, thesuffix data may contain data bits whose combination (e.g., . . . , 1, 0,1, 0, 1, 0, . . . ,) enables restoration of the genuine clock pulsesoriginally produced in and used by the in-vivo device with which thedata recorder operates. CRM 420 may use data bits of the suffix data, orany other data bits, to restore the in-vivo device's master clock signalgenerated by a master clock generator identical or similar to, forexample, master clock generator (MCG) 310 of FIG. 3C. CRM 420 mayinclude a phased lock loop (“PLL”). The PLL may output a clock signalwhose frequency may be determined based on, or tuned using, the databits. Tuning the PLL may be performed continually (e.g., by using databits in each data frame) or once in a while (e.g., once in k dataframes, where k=1, 2, 3, 4, . . . ). EOT detector 430 may use suffixdata bits to identify EOT times, and to produce a reset signal R′(t)332′ that corresponds to the EOT times. Reset signal R′(t) 332′ may be arestored version of reset signal R(t) 332 of FIGS. 3C and 3D since theEOT times detected by EOT detector 430 correspond to the EOT times atthe in-vivo device. By way of example, reset pulse 382′ of FIG. 4 is arestored version of reset pulse 382 of FIG. 3D.

Pulse counter 440, count comparator 450, and sensing window signal (SWS)generator 470 may respectively function like clock counter 320, countcomparator 340, and SWS generator 360 of FIG. 3C. The values N_3 andN_4, which may be stored in memory 460 and used by count comparator 450,may respectively be identical to the values N_1 and N_2, which may bestored in memory 350 and used by count comparator 340 of FIG. 3C. Byusing the values N_3 and N_4 count comparator 450 may output a timeindication each time the value of pulse counter 440 reaches one of thevalues N_3 and N_4, and sensing window signal (SWS) generator 470 mayuse the time indications output by count comparator 450 to produce acorresponding sensing window signal W′(t) (signal W′(t) is shown at362′). Sensing window signal W′(t) is a restored, or recovered, versionof sensing window signal W(t) (signal W(t) is shown in FIG. 3D and at362 in FIG. 3C). For various reasons (e.g., latency, etc.), the restoredsensing window signal W′(t) may lag behind sensing window signal W(t),as shown, for example, in FIG. 8, which is described below. However, thevalues of N_3 and N_4 may be set or adjusted (e.g., by calculation orempirically) such that they accommodate for the delay (e.g., minimizethe delay to an acceptable, manageable, or ignorable value).

FIG. 5 shows a method for synchronizing between an in-vivo device and alocalization signal generating system according to an exampleembodiment. At step 510, the in-vivo device (e.g., in-vivo device 110)may be activated and the in-vivo device may execute, generate orcommence a work cycle similar, for example, to work cycle 370 of FIG.3D. The work cycle may have a time period during which the in-vivodevice may transmit a data frame. At step 520, a data recorder (e.g.,data recorder 120) may receive the data frame transmitted from thein-vivo device. At step 530, the pulses of the master clock, which mayoriginally be used by the in-vivo device to synchronize its operation,may be restored (e.g., by MCRR 410) in order to facilitate generation orcreation of a synchronization signal by a synchronization signal unitsimilar to SSU 124 of FIG. 1.

At step 540, a localization signal may be generated by a localizationsignals source (LSS) similar to LSS 130 at a time and for a durationspecified, indicated, or represented by the synchronization signal. Asdiscussed above, the synchronization signal generated and output by, forexample, SWS Generator 470 (e.g., W′(t)) and the sensing window signalW(t) used by the in-vivo device may be derived from a common time‘source’ or time indicator (e.g., ‘transmission-to-idle’ transitions).Therefore, at step 550 the in-vivo device may activate sensing coilsassembly (SCA) 112 to sense the localization signal substantially at thesame time and substantially for the same period as specified, indicated,or represented by the synchronization signal. At step 560, the in-vivodevice may pre-process the sensed localization signal (e.g., the EMFsignal(s) induced, for example, in SCA 112), temporarily storecorresponding localization data, and transmit the localization data(e.g., to the data recorder) during a transmission period of the next orsubsequent work cycle, or during a transmission period of some otherwork cycle. Generation and transmission of work cycles may continue aslong as possible or as long as required, as per step 510, and steps 520to 560 may be repeated for each work cycle or for selected work cycles.

A method for synchronizing between an in-vivo device and a localizationsignal generating system according to another example embodiment mayinclude defining a sensing window during which the in-vivo device maysense a localization signal; intermittently transmitting data from thein-vivo device; restoring, by a receiver (e.g., data recorder) externalto the in-vivo device, the sensing window from data (e.g., a data frame)transmitted by the in-vivo device; producing, by the receiver, based onthe restored sensing window, a synchronization signal to signal thesensing window; transferring the synchronization signal to alocalization signals source (LSS); and generating by the localizationsignals source, and sensing by the in-vivo device, a localization signalduring the sensing window. Any data that is transmitted as, or in theform of, data frames may be regarded as data that is transmittedintermittently. For example, image data may be regarded as data that istransmitted intermittently because it is transmitted using image frames.

FIG. 6 shows a timing diagram 600 used internally by an in-vivo deviceaccording to an example embodiment. Graph 610 is a master clock (MSCLK)signal. MSCLK signal may be used internally by the in-vivo device tosynchronize the activities performed by the in-vivo device. Graph 620 isa main signal that is timed based on MSCLK signal 610. That is, MSCLKsignal 610 enables timing the logic value ‘1’, or ‘high’ state, of mainsignal 620, as shown at 622 and 624, and the logic value ‘0’, or ‘low’state, of main signal 620, as shown at 626. MSCLK signal 610 may begenerated by a timing unit similar to master clock generator (MCG) 310of FIG. 3C.

The duration of the high states of main signal 620 (e.g., high states622 and 624) may be set to comply with the transmission period discussedabove (e.g., in connection with transmission periods 371 and 373 of FIG.3D). The duration of the low states of main signal 620 (e.g., low state626) may be set to comply with the idle periods discussed above (e.g.,in connection with idle period 372 of FIG. 3D). Time cycle T_(CYCLE)628, which is an example work cycle, includes idle period 626 andtransmission period 624.

Due to the relatively high frequency (e.g., in the order of megahertz)at which master clock generators typically operate, they tend tosuperimpose electrical noises on electrical signals, the result of whichmay be a degraded signal-to-noise (S/N) ratio. Disabling the output ofthe clock generator when it is not required, or limiting its use, for alimited time period within an idle period (e.g., within idle period626), may, therefore, mitigate that problem. Disabling the output of theclock generator, or limiting its use, may mean that the clock generatormay still produce clock pulses in order to keep track time, but thesepulses are not used to ‘clock’ (they are not distributed to) othercomponents. Temporarily disabling the output of the clock generator (orlimiting its use) may, therefore, increase, or improve, the receptionsensitivity of a receiver of the in-vivo device, and therefore maybeneficially be used by the in-vivo device to receive commands and/ordata from the data recorder. For example, during idle period 626 theoutput of the clock generator that generates MSCLK signal 610 may bedisabled for a time period 612 to improve the reception quality ofcommands and/or data from the data recorder, and, in general, to reduceelectrical noise in the in-vivo device.

Graph 630 is a signal (“DOWNLINK”) that may signal to the in-vivodevice's controller a time slot, or ‘downlink’ period, that has beenallocated in each idle period, or in selected idle periods (e.g.,downlink period 632 in selected idle period 626), during which thein-vivo device may receive commands and/or data from the data recorder.Graph 640 is a window signal that may signal to the in-vivo device'scontroller a time slot during which the in-vivo device may processcommands and/or data that the in-vivo device may receive during, forexample, downlink period 632 from the data recorder. The data recordermay occasionally transmit commands and/or data to the in-vivo device,and the in-vivo device may reserve downlink periods similar to downlinkperiod 632 in order to be able to receive the commands and/or data, oncetransmitted by the data recorder. Graph 650 is a signal (“SENSING”)similar to sensing window signal (SWS) 364 of FIG. 3D. Sensing signal650 may signal to the in-vivo device's controller a time slot (e.g., asensing window) during which the in-vivo device may prepare to receivelocalization signals (e.g., from localization signals source (LSS) 130),process the localization signals, and store corresponding localizationdata in a storage unit (e.g., in storage unit 240). Graph 660 is awindow signal that may signal to the in-vivo device's controller a timeslot (e.g., an imaging window) during which the in-vivo device maycapture an image by, for example, activating, during window 662, theillumination source (e.g., light/illumination source 214) and the imager(e.g., imager 212), and executing related processes (e.g., imagecapturing and processing, storing image data, etc.). Graph 670 depicts awindow signal similar to frame signal F(t) of FIG. 3B and FIG. 3D.Signal 670 may signal to the in-vivo device's controller a time slot(e.g., a transmission period) during which the in-vivo device mayactivate the transmitter (e.g., transmitter 250) and transmit a dataframe (e.g., image frame). The data frame may include any combination ofimage data, localization data, prefix data bits, suffix data bits, andother types of data.

The time specifics of downlink pulse 634 (and of other like pulses);e.g., onset time T1 and termination time T2 of pulse 634, may bedetermined by using a timing unit similar to timing unit 300, with thecount values N_1 and N_2 replaced by count values corresponding to orrepresenting times T1 and T2 (which are measured or calculated relativeto a predetermined reference time). Pulse/window 642 (and likepulses/windows), pulse/window 652 (and like pulses/windows),pulse/window 662 (and like pulses/windows), and pulse/window 672 (andlike pulses/windows) may be timed like pulse/window 634; that is, byusing corresponding count values N_i, N_j.

FIG. 7 shows a timing diagram 700 that is used internally by a datarecorder according to an example embodiment. Graph 710 is a recoveredversion of the main signal 620 in FIG. 6. Sensing window 712 isfunctionally similar to sensing window 342 of FIG. 3B, where the sensingwindow starts at time Tw3 and terminates at time Tw4, and to sensingwindow 652 of FIG. 6. Down-transition 714 (at time 702) may be used toreset a counter and trigger another count interval to determine the timeboundaries of sensing window 712.

In one embodiment a location of an in-vivo device is determined by alocalization system by using the X,Y,Z coordinates system, and thelocalization signals source (e.g., LSS 130) transmits threeelectromagnetic signals: one signal that is associated with orcorresponds to the X-axis, and such signal is referred to herein as“X-signal”; a second signal that is associated with or corresponds tothe Y-axis, and such signal is referred to herein as “Y-signal”; and athird signal that is associated with or corresponds to the Z-axis, andsuch signal is referred to herein as “Z-signal”. The X-signal, theY-signal, and the Z-signal may be transmitted one signal at a time, forexample in order for them to be correctly interpreted by the in-vivodevice. The overall time slot 712 allocated for sensing and processinglocalization signals may be partitioned to three sensing sub-windows724, 734, and 744. Each sensing sub-window may be allocated to aparticular localization signal. For example, sensing sub-window 724 maybe allocated to sense the X-signal; sensing sub-window 734 may beallocated to sense the Y-signal; and sensing sub-window 744 may beallocated to sense the Z-signal. The X-signal, Y-signal, and Z-signalmay be transmitted by a localization signal source (LSS) as per three,separate, synchronization signals 720, 730, and 740. The time specificsof synchronization signals 720, 730, and 740 may be measured from orrelative to, for example, reference time 702. One synchronization signalmay be used instead of the separate synchronization signals 720, 730,740, and such a synchronization signal may embody (a superposition of)the separate synchronization signals.

In general, description in this document regarding the sensing windowmay in some embodiments apply to each sensing sub-window. The term“sensing sub-window” is merely used herein as a matter of convenience.Time specifics of a sensing sub-window may be measured by counting thesame clock pulses that are used for measuring the time specifics of the‘larger’ sensing window, and relative to the same time reference that isused for measuring the time specifics of the sensing window. ‘Timespecifics’ may be explicitly expressed, measured or counted in timeunits (e.g., in seconds; e.g., 2 milliseconds), or implicitly, as anumber of clock pulses or pulse count (e.g., 580 pulses). Measuring timethat elapses relative to a reference time is equivalent to countingclock pulses relative to a reference, or initial, count value of acounter. Stating that sensing electromagnetic localization signal isdone during a sensing window (or during a sensing sub-window) isanalogous to stating that sensing the electromagnetic localizationsignal is done during a time period coinciding with the sensing window(or with the sensing sub-window).

The in-vivo device may start sensing the X-signal at time Tx and for theduration of pulse 722, and use the remaining time 726 of sub-window 724to process the sensed X-signal and to store corresponding localizationdata in a storage unit. Likewise, the in-vivo device may start sensingthe Y-signal at time Ty and for the duration of pulse 732, and use theremaining time 736 of sub-window 734 to process the sensed Y-signal andto store corresponding localization data in a storage unit. Likewise,the in-vivo device may start sensing the Z-signal at time Tz and for theduration of pulse 742, and use the remaining time 746 of sub-window 744to process the sensed Z-signal and to store corresponding localizationdata in a storage unit. The up-transitions of pulses 722, 732, and 742(which are respectively shown at, or respectively correspond to timesTx, Ty, and Tz) and the down-transitions (or duration) of each sensingsub-window may be determined by, for example, comparing correspondingpulse count values to time specifics that define the sensingsub-windows.

FIG. 8 shows localization signals and resulting sensed signals (EMFsignals) that are timed according to an example embodiment. Signal 810is an example main signal that is generated in an in-vivo device (e.g.,in in-vivo device 110). With main signal 810 is associated a sensingwindow 812, during which electromagnetic localization signals may begenerated and transmitted (e.g., by LSS 130) and concurrently sensed byone or more sensing coils of the in-vivo device (e.g., by SCA 112).

Signal 820 (a recovered main signal) is a signal restored, for example,by a data recorder (e.g., data recorder 120), for example by using databit, or data bits, (e.g., suffix data or any other group of data bits)embedded in data frames. The data bit(s) used for the signal restorationmay be chosen such that the restored signal temporally resembles mainsignal 810 as much as possible in terms of shape and timing. A sensingwindow (e.g., sensing window 822) is also associated with main signal820. Due to various factors (e.g., latency, etc.), main signal 820 (therestored main signal) may lag behind main signal 810 (main signal 810 isthe in-vivo device's ‘genuine’ main signal). An example lag time ΔTbetween signal 810 and signal 820 is shown at 830. As a result of lagtime 830, sensing window 822 may also lag behind sensing window 812. Byway of example, sensing window 822 starts at time t1, whereas sensingwindow 812 starts at time t0, where t1−t0=ΔT (or t1−t0≅ΔT). To continuethe example, the in-vivo device may transition to the sensing mode attime t0 (to sense localization signals), and the system transmitting thelocalization signals based on main signal 820 may start transmitting thelocalization signals only at time t1. However, since ΔT is short (e.g.,in the order of nanoseconds (nSec.), e.g., a few nSec.), it may havelittle or no impact on the electromagnetic signals sensing process and,therefore, on its results. The in-vivo device may reduce the lag time ΔT(i.e., fine tune to, or adjust or adapt sensing window 812 to sensingwindow 822; e.g., ‘move’ sensing window 812 to the right hand side(later in time) to coincide or overlap with sensing window 822) orcompensate for it by manipulating (e.g., adjusting) the pertinent pulsecount values. Data representative of the adjusted number(s) of pulses ofthe clock signal may be sent (transmitted, or otherwise communicated) tothe in-vivo device (e.g., from a data recorder), or to the data recorder(e.g., from the in-vivo device).

A localization signals source (e.g., LSS 130) may transmit localizationsignals in short bursts. For example it may transmit, during aparticular work cycle, a signal burst pertaining to the X-axis, then asignal burst pertaining to the Y-axis, then a signal burst pertaining tothe Z-axis, and then it may repeat the sequence of signal bursts foreach work cycle, or for selected work cycles. By way of example,electromagnetic localization signal burst 842 may be associated with theX-axis, and it may be transmitted first (starting at time t1), forexample for a period set or governed by a pulse similar to pulse 722 ofFIG. 7; electromagnetic localization signal burst 844 may be associatedwith the Y-axis, and it may be transmitted second, for example startingat a time and for a period set or governed by a pulse similar to pulse732 of FIG. 7; and electromagnetic localization signal burst 846 may beassociated with the Z-axis, and it may be transmitted third, for examplestarting at a time and for a period set or governed by a pulse similarto pulse 742 of FIG. 7. By way of example, each of localization signalbursts 842, 844, and 846 may include four cycles, as shown in FIG. 8, orother numbers of cycles (e.g., less than four cycles, or more than fourcycles).

At time t0 or a short time after time t0 (e.g., at t1), the in-vivodevice may start sensing electromagnetic localization signal burst 842:the resulting electromotive force (EMF) signal induced in a sensing coilof the in-vivo device by localization signal burst 842 is shown at 852.Shortly after localization signal burst 842 is terminated, the in-vivodevice may process the sensed localization signal and thereafter maystart sensing the next burst (electromagnetic localization signal burst844): the resulting EMF signal induced in a sensing coil of the in-vivodevice by localization signal burst 844 is shown at 854. Likewise,shortly after localization signal 844 is terminated, the in-vivo devicemay process the sensed localization signal and thereafter may startsensing electromagnetic localization signal 846: the resulting EMFsignal induced in a sensing coil of the in-vivo device by localizationsignal burst 846 is shown at 856. Since an in-vivo device may berotated, tilted, and rolled 360 degrees, an induced EMF signal may havea certain phase for a particular direction, alignment, or orientation ofthe related sensing coil, and an opposite phase for the oppositedirection, alignment, or orientation of the sensing coil. For thisreason, FIG. 8 shows two potential induced EMF signals for each oflocalization signal bursts 842, 844, and 846.

Practically, only one EMF signal can be induced in a sensing coil of thesensing coils assembly (SCA) of the in-vivo device at a time. If thesensing coils assembly (SCA) used by an in-vivo device includes n (n>1)sensing coils, each localization signal may induce an EMF signal in oneor more of the n sensing coils. For example, if there are threelocalization signals (e.g., localization signals 842, 844, and 846) andn=3 (the SCA includes three, preferably mutually perpendicular, sensingcoils), then up to nine EMF signals may be induced in the SCA altogetherduring sensing window 812: three EMF signals may simultaneously beinduced in the three sensing coils by localization signal 842 during afirst sensing sub-window; three EMF signals may simultaneously beinduced in the three sensing coils by localization signal 844 during asecond sensing sub-window, and three EMF signals may simultaneously beinduced in the three sensing coils by localization signal 846 during athird sensing sub-window. For example, nine raw EMF signals such as rawEMF signals 852, 854, and 856 may be induced in the sensing coils of theSCA of the in-vivo device during each sensing window: EMFx1, EMFx2 andEMFx3 for the X-axis; EMFy1, EMFy2 and EMFy3 for the Y-axis; and EMFz1,EMFz2 and EMFz3 for the Z-axis. By “EMFxi”, “EMFyi” and “EMFzi” (i=1, 2,3) is respectively meant the EMF signals induced in the SCA's sensingcoils by the localization signals respectively associated with theX-axis, Y-axis, and Z-axis. Example EMF signals that are induced inthree sensing coils during a same sensing sub-window are shown in FIG.9, which is described below. (The localization signals used to generatelocalization data do not necessarily have to be sinusoidal, as shown,for example, at 842, 844 and 846; they may have other shapes. Forexample, signal cycles making up a localization signal may substantiallybe triangularly shaped.)

Each burst of localization signal may include M cycles, where M may beequal to or greater than one. By way of example, each of localizationsignal bursts 842, 844, and 846 includes four cycles, in which exampleM=4. Each signal burst may induce, for example, three raw EMF signals(e.g., in SCA 112). At least one cycle has to be read from the sensingcoils for each coordinate, direction, or orientation of the in-vivodevice in order to be able to correctly deduce the coordinate, directionor orientation of the in-vivo device. However, reading one cycle foreach coordinate/direction/orientation may not suffice. In general, thelarger M, the higher the reliability of the reading of the induced EMFsignals, and therefore the more accurate their interpretation. However,as discussed herein, the sensing window may be subjected to stricttiming constraints, and using an EMF localization signal that includestoo many cycles may result in one or more cycles exceeding the permittedboundaries of the sensing window or the permitted boundaries of thesensing sub-windows. That is, a sensing window, or sensing sub-window,can accommodate a maximal number, Mmax, of cycles. The aforesaid problemmay be mitigated (e.g., Mmax may be increased) by shortening the cyclesof the localization signals by increasing their frequency, f_(LOC).Therefore, there is a tradeoff between the frequency of the localizationsignals (f_(LOC)), the maximal number (Mmax) of cycles that eachlocalization signal burst is allowed to include, and the number of theused localization signals (e.g., three localization signals that may berelated to the X,Y,Z coordinates system). The number of cycles (M)included in localization signal bursts may also depend on, andadjustable according to, the image capturing rate, or FPS value. Ingeneral, the higher the image capturing rate, the shorter the time thatcan be allocated for the sensing window and, therefore, the lesser thepermitted number of the cycles of each signal burst. For example, if asensing window's width (duration) is, for example, 5 milliseconds andthe localization signals' frequency is, for example, 5 kilohertz (KHz),then the sensing window may theoretically be able to accommodate 25cycles (M=25). Since processing of each EMF signal may take place inbetween bursts of localization signals, the practical usable number ofcycles may be lower. For example the practical usable number of cyclesmay be 12, as shown in FIG. 8, where each of the three examplelocalization signal bursts includes four cycles.

FIG. 9 shows an example of three EMF signals 910, 920, and 930 that aresimultaneously induced (e.g., by a same localization signal burst) on asensing coils assembly (SCA) that includes three sensing coils. For thesake of demonstration, EMF signals 910, 920, and 930 are graphicallyshown one under the other and having the same peak-to-peak amplitude970. However, in a case where sensing coils have different spatialorientation (e.g., they may be mutually perpendicular), each sensingcoil may, in general, output an EMF signal with a different peak-to-peakamplitude even if the sensing coils are subjected or exposed to the samelocalization signal.

As explained above, one localization signal may be generated outside thein-vivo device and sensed by the sensing coils assembly (SCA) of thein-vivo device for the X-axis, another localization signal may likewisebe generated and sensed for the Y-axis, and another localization signalmay likewise be generated and sensed for the Z-axis. That is, detectingthe X,Y,Z coordinates of an in-vivo device may require generation ofthree localization signals by localization signals source (LSS) 130: onefor the X-coordinate, another for the Y-coordinate, and another for theZ-coordinate. Depending on the orientation of the sensing coils of SCA112 relative to LSS 130, whenever a particular localization signal isgenerated, it may induce one, two or three EMF signals: one EMF signalon the sensing coil associated with the X-axis, another EMF signal onthe sensing coil associated with the Y-axis, and another EMF signal onthe sensing coil associated with the Z-axis. By way of example, EMFsignals 910, 920, and 930 are assumed to be induced on three sensingcoils by a same localization signal. For example, EMF signals 910, 920,and 930 (or similar EMF signals) may be induced by the localizationsignal associated with the X-axis, in which case the X-coordinate of thein-vivo device may be deduced from EMF signals 910, 920, and 930. If EMFsignals 910, 920, and 930 (or similar EMF signals) are induced by thelocalization signal associated with the Y-axis, then the induced EMFsignals enable determining the Y-coordinate of the in-vivo device, andif EMF signals 910, 920, and 930 (or similar EMF signals) are induced bythe localization signal associated with the Z-axis, then the induced EMFsignals enable determining the Z-coordinate of the in-vivo device. Thatis, a set of three (or other numbers of) EMF signals may serve as abasis for determining or deducing a particular coordinate (ororientation) of the in-vivo device. EMF signals 910, 920, and 930 (whichmake up an example set of EMF signals) may enable determination of onecoordinate of the in-vivo device; another set of three (or other numbersof) EMF signals may serve as a basis for determining or deducing anothercoordinate (or orientation) of the in-vivo device, and so on.

The peak-to-peak amplitudes of EMF signals 910, 920 and 930, may bedetermined by a processor or controller (for example by controller 260of in-vivo device 110), and the pertinent coordinate (be it theX-coordinate, the Y-coordinate, or the Z-coordinate) may be calculatedor deduced (e.g., by the in-vivo device or externally) from theseamplitudes, for example by using a suitable set of voltage-to-coordinateconversion formulas or tables. The in-vivo device may determine thepeak-to-peak amplitudes of EMF signals 910, 920, and 930 by sampling atleast a portion of each EMF signal and processing the samples. Then, thein-vivo device may store a corresponding sensing data for each sampledEMF signal in a storage device. The in-vivo device may sample each ofEMF signals 910, 920, and 930, for example by allocating a separatesampling circuit, or sampler, for each sensing coil, or by using acommon sampler. A sampler may include at least a sample-and-hold (S&H)circuit for analogically sampling EMP signals, and an analog-to-digitalconverter (ADC) for converting the analog sample values to digital data.A sampler may also include a preamplifier for amplifying the EMF signalsbefore they are sampled by the S&H circuit.

In one embodiment EMF signals 910, 920, and 930 are sampled using acommon sampler and the localization signals start from zero value andtheir first half is positive. Since the frequency, f_(loc), andtherefore the wavelength (e.g., wavelength, λ, 940), of the localizationsignals are known in advance, the positive peak, or crest, of the EMFsignal may be expected (e.g., by using count comparator 340) to occur attime Tc. Therefore, the in-vivo device may schedule the sampling processto commence a short time before time Tc, for example at time Ts, and toterminate a short time after time Tc, for example at time Tt. Selectinga suitable sampling time (e.g., T_(SAMPLE), shown at 960) may enable,for example, sampling the positive half of EMF signal 910 four times tofind; e.g., by interpolation, a crest point; e.g., crest point 980, andsampling the negative half of EMF signal 910 four times to find, e.g.,by interpolation, a lowest point in signal 910; e.g., point 982.

Likewise, sampling time T_(SAMPLE) 960 may also enable, for example,sampling the positive halves of EMF signals 920 and 930 four times (todetect or deduce the respective crest points), and sampling the negativehalves of EMF signals 920 and 930 four times (to detect or deduce therespective lowest points). Each group of ‘positive’ samples that areassociated with the same EMF signal and each group of ‘negative’ samplesthat are associated with the same EMF signal may undergo aninterpolation process to deduce or determine the pertinent crest pointand lowest point, as the case may be. For example, positive samplesgroup 934 enables determining the crest point 936, and negative samplesgroup 992 enables determining the lowest point of EMF signal 930 (e.g.,point 990).

A sampled point may be a crest point (e.g., crest point 936) or a lowestpoint, and if it is neither of those points, the crest point, or thelowest point, may be interpolated from the pertinent group of samples(e.g., crest point 980 and lowest point 990 may be interpolated from thepertinent samples group). Knowing the crest point and the lowest pointsof each EMF signal enables calculating its peak-to-peak amplitude (e.g.,peak-to-peak amplitude 970). The order at which the EMF signals aresampled may be ‘cyclic’, with EMF signal 910 sampled first (e.g., atpoint 912), then EMF signal 920 sampled second (e.g., at point 922),then EMF signal 930 sampled third (e.g., at point 932), EMF signal 910sampled again (e.g., at point 914), and so on.

Controller 260 of in-vivo device 110 may sample each cycle of each EMFsignal, calculate, for example, an average peak-to-peak amplitude foreach EMF signal (and nine average amplitudes in total for each workcycle or sensing window) and, while in the idle period (for example),store raw sensing data (raw localization data) corresponding to orrepresenting the nine average peak-to-peak amplitudes. Controller 260may embed the raw sensing/localization data in a data frame and transmitthe data frame, for example, to data recorder 120, during one of thetransmission periods following the idle period. Processor 290 of datarecorder 120 may process the received raw sensing/localization datacorresponding to or representing the nine average peak-to-peakamplitudes to deduce the X,Y,Z coordinates of the in-vivo device.Alternatively, data recorder 120 may transfer the rawsensing/localization data to another system for analysis.

Alternatively, controller 260 may process the EMF signals and deducetherefrom, for example, the X-Y-Z coordinates and/or the orientation ofthe in-vivo device. Controller 260 may, for example while the in-vivodevice is in the idle period, store localization data that explicitlyrepresent the X,Y,Z coordinates (and optionally the orientation) of thein-vivo device, and embed the data in a data frame. Controller 260 maytransmit the data frame, for example, to data recorder 120, during atransmission period. Transmitting to the data recorder data thatexplicitly/already represent the X,Y,Z coordinates (and optionally theorientation) of the in-vivo device obviates the need for deducing theseparameters by the data recorder or by another system.

FIG. 10 shows an in-vivo device 1000 that is configured according toanother example embodiment. In-vivo device 1000 may include a FPS lookuptable (“FLT”) 1010 in addition, for example, to SCA 112, timing unit114, imager 212, lighting source 214, frame generator 220, controller260, storage unit 240, and other components that are shown in FIG. 2(e.g., transceiver 250). FLT 1010 may facilitate adjustment of thesensing window and/or sensing sub-windows according to the used imagecapturing rate.

An in-vivo device may be capable of changing the image capturing rate orthe rate at which the in-vivo device transfers images to the datarecorder (that rate being referred to as, or measured in, frames persecond (FPS)). The image capturing rate may change, for example, basedon the location of the in-vivo device in the GI system and/or based onthe imaged object and/or based on movement of the in-vivo devicerelative to the GI system, etc. A change in the image capturing rate maynecessitate a change in the sensing window. That is, the time specificsof the sensing window may have to change (e.g., the window may have tobe moved and its width or duration may have to be changed) toaccommodate for changes in the image capturing rate or FPS. Controller260 may receive a command 1020 (e.g., from the data recorder; e.g.,during downlink window 634), for example, to change a current FPS valueto another value. For example, controller 260 may receive a command 1020to change the FPS rate from 4 FPS to 8 FPS, or from 2 FPS to 8 FPS, etc.Controller 260 may independently change the FPS rate, for example, basedon a physical parameter (e.g., pH, temperature, pressure, movement,etc.) reaching a predetermined limit, or being within a specified range,or exceeding a specified range.

Referring to FIG. 6 again, if the FPS rate is increased, sensing window652 may have to be moved to the left (on the time axis, e.g., prior intime) and it may have to be temporally narrower (shorter in duration) inorder not to interfere with, for example, pulses/windows 642 and 662.Time specifics of sensing windows and/or time specifics of sensingsub-windows may be predetermined for different FPS values such that aparticular sensing window, or a particular set of sensing window andrelated sensing sub-windows may be associated with a particular FPSvalue.

FLT 1010 may contain a list of FPS values and a list of pairs of countvalues (e.g., pairs [N_p11, N_p21]; [N_p12, N_p22]; [N_p13, N_23]; . . ., etc.), a pair per FPS, where each pair of count values may uniquelyrepresent timing specifics of a different sensing window or sensingsub-window. “Different sensing window” and “different sensingsub-window” also refer to a sensing window and sensing sub-window thatare temporally ‘moved’, adjusted, or adapted to accommodate for a newFPS rate, and to time specifics corresponding to, representing, ordefining, the moved/adjusted/adapted sensing window or sensingsub-window. If three (or other numbers of) sensing sub-windows areadditionally or alternatively used, FLT 1010 may include more than onepair of count values per FPS value (e.g., three pairs of count values,four pairs of count values, etc.). Each FPS value may, therefore, pointto or be related to or associated with a set of pairs of count values.The set of pairs of count values may include pairs of count valuesrelated, for example, to a sensing window and/or to one or more sensingsub-windows. FLT 1010 may be stored, for example, in storage unit 240.If an in-vivo device receives a command (e.g., command 1020), forexample from a data recorder, to use, or to transition to, a FPS ratethat is not listed in PLT 1010, the in-vivo device (e.g., controller260) may interpolate the time specifics or count values of the sensingwindow from the FPS values and from the pairs of count values that arelisted in FLT 1010.

FIGS. 11A-11B show timing diagrams associated with the sensing windowadaptation of the in-vivo device of FIG. 10. FIG. 11A shows a work cycleof an in-vivo device for a FPS value equal to FPS_1 (e.g., FPS_1=4frames per second). The work cycle includes an idle period 1110 and atransmission period 1120. FIG. 11A also shows an example sensing window1130 with an example pair of count values Ns1 and Ns2 that respectivelyrepresent particular starting time Ts and termination time Tt. Asdiscussed in connection with FIG. 10, count values may be selected ordetermined per FPS value. In one embodiment count values Ns1 and Ns2 areselected or determined for a FPS value equal to FPS_1 (e.g., FPS_1=4frame per second). Time specifics of sensing window 1130 may be constantor they may be adjusted or varied, for example, contingent on a rate(FPS) at which the in-vivo device transmits data (e.g., image data), asdemonstrated in FIG. 11B, which is described below.

FIG. 11B shows a working cycle of the in-vivo device for a FPS valueequal to FPS_2, where FPS_2>FPS_1 (e.g., FPS_2=8 frames per second).Accordingly, idle period 1140 is shorter than idle period 1110. (Sincetransmission periods do not necessarily depend on the FPS value (theymay depend on other factors; e.g., compression of data, amount of data),the same transmission period 1120 is shown unchanged in FIG. 11B.) Byway of example, FIG. 11B shows the sensing window 1130 of FIG. 11Aadjusted in accordance with the adjusted work cycle (the adjusted workcycle is shown at 1142), by ‘moving’ it to the left, e.g., earlier intime (the moved sensing is shown at 1130′). Moving sensing window 1130is implemented by respectively adjusting count values N1 and N2 to countvalues N1′ and N2′. Count values N1′ and N2′ respectively representadjusted starting time and adjusted termination time of adjusted sensingwindow 1130′. ‘N0’ in FIGS. 11A-11B is an initial count value. Asexplained above (for example in connection FIG. 3D), the initial valueof the pulse counter may be ‘0’, and the counter may be reset to theinitial value, for example during each work cycle. The reset time mayoverlap or coincide with, or represent, the reference time relative towhich time specifics are measured or calculated. Time specifics ofsensing time sub-windows may be adjusted in the same manner as the timespecifics of the sensing window, for example they may be adjustedproportionately to the adjusted time specifics of the sensing window,and, in that sense, the time specifics of the sensing time sub-windowsare also adjusted or varied contingent on the data transmission rate,FPS, of the in-vivo device. Data representing the adjusted timespecifics, or data representing the pertinent adjusted counted number(s)of pulses of the used clock signal, may be sent (e.g., transmitted, orotherwise communicated) to the in-vivo device (e.g., from a datarecorder), or to the data recorder (e.g., from the in-vivo device).

As discussed, each burst of localization signal may include M cycles. Insome embodiments, the frequency, f_(LOC), of the localization signalsmay be constant, and the value of M may be inversely dependent on theimage capturing rate: the higher the image capturing rate, the lower thevalue of M. The image capturing rate may controllably be adjustablebetween a minimum FPS limit FPSmin (e.g., FPSmin=2 FPS) and a maximumlimit FPSmax (e.g., FPSmax=48 FPS), and M may be inversely adjustedbetween a minimum limit Mmin (e.g., Mmin=2 cycles) and a maximum limitMmax (e.g., Mmax=6 cycles), where Mmin and Mmax are respectivelyassociated with FPSmax and FPSmin. In other embodiments, the frequency,f_(LOC), of the localization signals may be variable to enablemaintaining the value of M: if the image capturing rate is increased,f_(LOC) may be increased as well in order to maintain the value of Meven though increasing the image capturing rate may result in narrowedsensing windows or narrowed sensing sub-windows.

As discussed, when the image capturing rate changes, time specifics ofthe sensing window, or sensing sub-windows, may have to be changed aswell. A list of time specifics may be stored in, for example, thein-vivo device, and the in-vivo device may transfer the time specificsin force, for example, to the data recorder, or vice versa. In addition,if the frequency of the localization signals is adjustable and the imagecapturing rate changes from a current FPS to another FPS, the datarecorder may send a message to the localization signals system (LSS),notifying it of a frequency of the localization signals that correspondsto the other FPS. In response to the message sent by the data recorder,the LSS may generate localization signals at the designated frequency.In another embodiment, the frequency of the localization signals may beconstant, in which case the number of cycles of the localization signal,per each signal burst, may be adjustable in response to an adjustment ofthe sensing time window or sensing time sub-window. If the PFS ratechanges, data that represents the new (adjusted) frequency of thelocalization signals or the new (adjusted) number of cycles oflocalization signal bursts (whichever the case may be) may betransmitted to the localization signals source.

FIG. 12A and FIG. 12B depict a printed circuit board (“PCB”) of anin-vivo device that is configured to sense localization signals. FIG.12A depicts an example cross-like multilayered imaging and sensingprinted circuit board (MISP) 1200 of an in-vivo device similar toin-vivo imaging device 110. MISP 1200 may include 1-layer portions orsections even though it is generally referred to as a ‘multilayered’PCB. MISP 1200 may be rigid-flex, which means that portions, parts orsections thereof may be rigid whereas other portions, parts or sectionsthereof may be flexible enough to allow them to be folded into acylinder-like structure. MISP 1200 may be full-flex, which means thatall of its portions/parts/sections are flexible. By way of example, MISP1200 is shown including two printed circuit board (“PCB”) branches that‘cross’, or intersect, each other: imager section 1240 and sensing coilsassembly (SCA) section 1250.

Imager section 1240 includes at least imaging circuitry 1260, for whichreason section 1240 is referred to as ‘imager section’. Imager section1240 may include, for example, three rigid sections, designated as 1202,1204 and 1206, that may be multilayered, and two flexible sections,designated as 1294 and 1296, that may also be multilayered. Flexiblesection 1294 may connect rigid sections/portions 1204 and 1206 and bepartly sandwiched between layers of these sections/portions. Section1296 may connect rigid sections 1202 and 1204 and be partly sandwichedbetween layers of these sections. The other side of sections 1202, 1204,and 1206 may also accommodate additional elements and/or components, asdepicted in FIG. 12B.

Imaging circuit 1260, which may include an imager similar to imager 212of imaging device 110, may be mounted, for example, on rigid section1206. An illumination source similar to illumination source 214 ofin-vivo device 110 may also be mounted on rigid section 1206, as shown,for example, at 1270. By way of example, the illumination source mountedon rigid section 1206 includes four light sources which areequidistantly and circle-wise positioned on rigid section 1206. Otherelectronic components of the in-vivo device (e.g., ASIC, controller,transmitter, crystal oscillator, memory, etc.) may be mounted, forexample, on section 1204 and/or on section 1202.

SCA section 1250 includes sensing coils for sensing (localization)magnetic fields by which the location and/or orientation of the in-vivodevice may be determined By way of example, SCA section 1250 includeselectromagnetic sensing coil 1210 and electromagnetic sensing coil 1220.Electromagnetic sensing coils 1210 and 1220 are shown to be rectangular,but they need not be rectangular. The two sensing coils 1210 arecollectively referred to as sensing coil 1210 because the two sensingcoils 1210 may be electrically interconnected to functionally form oneelectrical component (i.e., one sensing coil). Likewise, the two coils1220 are collectively referred to as sensing coil 1220 because the twocoils 1220 may be electrically interconnected to functionally form onesensing coil. An additional sensing coil, which may functionally be partof SCA section 1250, may be mounted on, or be embedded, incorporatedinto, built into or formed in rigid section 1202 (the additional sensingcoil is shown at 1230). SCA section 1250 may be multilayered toaccommodate sensing coils of enlarged inductance to increase theelectromagnetic fields sensing sensitivity.

Flexible multilayered PCB dielectric substrate 1208 may accommodatesensing coils 1210 and 1220. Each PCB layer of multilayered PCBsubstrate 1208 may accommodate some of the coil turns of sensing coils1210 and/or some of the coil turns of sensing coils 1220. SCA section1250 is shown in FIGS. 12A and 12B outspread. Cylindrically folding SCAsection 1250 places some turns of sensing coils 1210 against/oppositeother turns of sensing coils 1210 (as shown in FIG. 12D) such that theirnormal lines substantially coincide with a same axis (e.g., ‘X’ axis ofthe X-Y-Z coordinates system), and some turns of sensing coils 1220against/opposite other turns of sensing coils 1220 such that theirnormal lines substantially coincide with another same axis (e.g., ‘Y’axis of the X-Y-Z coordinates system). (The opposing sensing coil 1220is hidden in FIG. 12D, and the planes of sensing coils 1220, thoughcurved a little, are generally perpendicular to the planes of sensingcoils 1210.)

FIG. 12B shows the other side of MISP 1200. By way of example, section1202 accommodates an antenna 1280 to facilitate radio frequency (RF)communication between the in-vivo imaging device and the data recorderor receiver with which the in-vivo imaging device operates; and sections1204 and 1206 respectively accommodate electrical springs 1290 and 1292.

Imaging section 1240 is shown in FIGS. 12A and 12B outspread, but, tofacilitate assembling of the in-vivo device, it is made foldable suchthat the rigid sections thereof may be stacked in a parallel manner suchthat rigid sections 1204 and 1206 may hold there between one or morebatteries while the lines normal to the planes of sections 1204 and 1206coincide with a longitudinal axis of the in-vivo imaging device. Whenrigid sections 1204 and 1206 are folded, electrical springs 1290 and1292 secure the one or more batteries in place, and electrically connectthem to the imaging device's electrical circuit (e.g., to MISP 1200).FIG. 12C shows a partly assembled in-vivo imaging device, with theimaging section 1240 folded/introverted and the SCA section 1250cylindrically folded. FIG. 12D shows the partly assembled in-vivo deviceof FIG. 12C with an optical head 1262 mounted on top of rigid section1206.

FIG. 13A shows a cross-sectional view of an in-vivo capsule 1300 with amagnetic steering unit (MSU) according to an example embodiment. By wayof example, the MSU of in-vivo capsule 1300 may include a magneticcarrier assembly (“MCA”) 1310; permanent ring shaped magnets 1320; andsensing coils assembly (SCA) section 1340. SCA section 1340 may beidentical or similar to SCA section 1250 of FIGS. 12A and 12B. FIG. 13Aalso shows an energy-picking coil 1330 that may be used to pick upelectrical energy from an external AC magnetic field for chargingbatteries 1302 for powering in-vivo capsule 1300. FIG. 13A also shows animager 1350; an illumination source 1360, which may be similar toillumination source 1270 of FIG. 12C (for example); an optical head1370, which may be similar to optical head 1262 of FIG. 12D; an opticalwindow 1380; a communication antenna 1390, which may be similar tocommunication antenna 1280 of FIG. 12B, and a transceiver circuit 1392.

FIG. 13B shows the in-vivo capsule 1100 of FIG. 13A with a multilayeredimaging and sensing printed circuit board (MISP) folded according to anexample embodiment. Regarding FIGS. 13A and 13B, like reference numeralsrefer to like elements/components/sections. The MISP of in-vivo capsule1300 includes SCA section 1350, which is shown cylindrically folded; animaging section that may be similar to imaging section 1240 of FIG. 12A.By way of example, the imaging section of in-vivo capsule 1300 includesPCB rigid sections 1301, 1303, 1305 (which may respectively be similarto rigid sections 1202, 1204, 1206 of FIG. 12A), and flexible/foldablesections 1307, 1309 (which may respectively be similar to sections 1296,1294 of FIG. 12A).

FIG. 14 shows an example magnetic maneuvering unit (MMU) 1400. Asdiscussed above in connection with FIG. 1, position/orientation data maybe transferred to a MMU in order for the MMU to use it as a feedback togenerate a magnetic field to steer, or maneuver, an in-vivo device to adesired location and/or orientation. The MMU may include a magneticfield generator to produce the required maneuvering magnetic forces andtoques, and a controller to control the operation of the magnetic fieldgenerator. By way of example, MMU 1400 may include a magnetic fieldgenerator that includes DC/AC magnetic coils 1410, 1420, 1430, 1440,1450, 1460, 1470, and 1480. DC/AC magnetic coils 1410 through 1480 maygenerate DC and AC magnetic fields to produce a magnetic field vortexwithin the ‘maneuvering space’ 1495 to maneuver an in-vivo device (e.g.,in-vivo device 110) swallowed by a patient lying on bed 1490. Themagnetic field vortex may controllably (e.g., as a function of thefeedback localization/orientation data) be moved, and its shape varied,by independently controlling the amplitude and direction of the currentsflowing through the magnetic coils 1410, 1420, 1430, 1440, 1450, 1460,1470, and 1480. Dynamic manipulation of the magnetic characteristics(e.g., location, direction, strength, orientation) of the magnetic fieldvortex changes the magnetic forces resulting from the interactionbetween the magnetic field vortex and the permanent magnets andeddy-current inducing magnets that reside in or is within the timeperiod defined by the maneuvered in-vivo device.

FIG. 15 shows a method for timing internal sensing, by an in-vivodevice, of externally generated/transmitted localization signalsaccording to an example embodiment. An in-vivo device may operateaccording to a sensing time window that is defined within a work cycleof the in-vivo device. The in-vivo device may time the work cycle byusing an internally generated clock signal, for example by countingpulses of a master clock signal. A reference time may be defined withinthe work cycle and used as a point of time from which time specifics ofthe sensing time window may be measured.

The in-vivo device may, during the work cycle, transmit, at step 1510, adata frame to an external receiver. The data frame may contain orinclude ‘restoration’ data to facilitate restoration, generation orproduction of a synchronization signal by the external receiver.Restoration, generation or production of the synchronization signal bythe external receiver may be based on the clock signal, the referencetime, and time specifics of the sensing time window. The in-vivo devicemay, during the work cycle, measure (at step 1520) time elapsing fromthe reference time by using the clock signal; sense (at step 1530) oneor more localization signals during a time period, which is measured orcalculated based on the elapsed time, that overlaps or coincides withthe time specifics of the sensing time window. The one or morelocalization signals may be externally transmitted, for example by anexternal localization signals source, at times and for a duration thatare specified by the synchronization signal. During the work cycle, thein-vivo device may also produce, at step 1540, localization data thatrepresents the sensed localization signals or a processed version of thesensed localization signals. Steps 1510 to 1540 may be repeated for eachwork cycle or for selected work cycles.

FIG. 16 shows a method for synchronizing between sensing of localizationsignals by an in-vivo device and generation of the localization signalsby an external localization signals source, according to an exampleembodiment. A receiver (e.g., data recorder) may be configured toreceive a stream of data frames from an in-vivo device, for example fromthe in-vivo device mentioned in the discussion of FIG. 15.

During the work cycle the receiver may receive, at step 1610, a dataframe from the in-vivo device. As explained in connection with FIG. 15,the in-vivo device may include in transmitted data frames restorationdata to facilitate restoration of the clock signal of the in-vivo deviceand the reference time. The receiver may, during the work cycle,identify and extract the restoration data from the data frame, and useit, at step 1620, to restore the clock signal and the reference time.The receiver may use the restored clock signal, restored reference timeand the time specifics (which are also used by the in-vivo device) torestore the sensing window (also at step 1620). The receiver may restorethe sensing time window, for example, by measuring, at step 1630, byusing the restored clock signal, the time elapsing from the restoredreference time, and comparing the elapsed time to the time specifics of(defining) the sensing window. The elapsed times matching the timespecifics of the sensing time window define the restored sensing timewindow.

Based on the elapsed time and time specifics of the sensing time window,the receiver may produce, at step 1640, a synchronization signal thatembodies the restored sensing time window. The receiver may transfer thesynchronization signal to an external localization signals source tocause it to generate one or more localization signals during a timeperiod that overlaps or coincides with the sensing time window, forsensing the one or more localization signals by the in-vivo deviceduring the sensing time window. Steps 1610 to 1640 may be repeated foreach work cycle or for selected work cycles of the in-vivo device, orfor each data frame, or for selected data frames, that is/are receivedby the data recorder.

FIG. 17 shows a method for synchronizing generation of a localizationsignal to sensing of the localization signal in an in-vivo deviceaccording to an example embodiment. The synchronization method mayinclude predefining, at step 1710, for an in-vivo device, a sensing timewindow during which the in-vivo device may internally sense alocalization signal originating from a localization signals sourceexternal to the in-vivo device; intermittently transmitting, at step1720, by the in-vivo device, data to an external receiver (e.g., datarecorder); restoring, at step 1730, by the receiver, the sensing timewindow from data transmitted by the in-vivo device; producing, at step1740, by the receiver, based on the restored sensing time window, asynchronization signal corresponding to the restored sensing timewindow, in order to signal the sensing time window to the localizationsignals source; transferring, at step 1750, the synchronization signalto the localization signals source; and producing, at step 1760, by thelocalization signals source, and concurrently sensing by the in-vivodevice, a localization signal during the sensing time window. Steps 1710to 1760 may be repeated for each work cycle or for selected work cyclesof the in-vivo device, or for each data frame or for selected dataframes, that is/are received by the data recorder.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle, depending on the context. By way of example, depending on thecontext, “an element” can mean one element or more than one element. Theterm “including” is used herein to mean, and is used interchangeablywith, the phrase “including but not limited to”. The terms “or” and“and” are used herein to mean, and are used interchangeably with, theterm “and/or,” unless context clearly indicates otherwise. The term“such as” is used herein to mean, and is used interchangeably, with thephrase “such as but not limited to”.

Embodiments of the invention may include an article such as a computeror processor non-transitory storage medium, such as for example amemory, a disk drive, or a USB flash memory, encoding, including orstoring instructions, e.g., computer-executable instructions, which whenexecuted by a processor or controller, carry out methods disclosedherein. For example, a system may include a non-transitory storagemedium such as storage unit 240, computer-executable instructions suchas timing unit 114 and a controller such as controller 260. Someembodiments may be provided in a computer program product that mayinclude a non-transitory machine-readable medium, having stored thereoninstructions, which may be used to program a computer, or otherprogrammable devices, to perform methods as disclosed above.

Having thus described exemplary embodiments of the invention, it will beapparent to those skilled in the art that modifications of the disclosedembodiments will be within the scope of the invention. Alternativeembodiments may, accordingly, include more modules, fewer modules and/orfunctionally equivalent modules. The present disclosure is relevant tovarious types of in-vivo devices (e.g., in-vivo devices with one or moreimagers, in-vivo devices with no imagers at all, etc.), and to varioustypes of receivers. Hence the scope of the claims that follow is notlimited by the disclosure herein.

The invention claimed is:
 1. A method for timing sensing of localizationsignals by an in-vivo device, the method comprising: by an in-vivodevice operating according to a sensing time window within a work cycleof the in-vivo device, the in-vivo device timing the work cycle using aclock signal and having defined within the work cycle a reference time,performing during the work cycle: (i) transmitting a data frame to areceiver, the data frame comprising data facilitating generation by thereceiver of a synchronization signal for an external localizationsignals source based on a clock pulse, the reference time, and on timespecifics of the sensing time window; (ii) measuring time elapsing fromthe reference time by using the clock signal; (iii) sensing, based onthe elapsed time, during a time period complying with the time specificsof the sensing time window, one or more localization signals externallytransmitted by the external localization signals source at times and forduration specified by the synchronization signal; and producinglocalization data representative of the sensed externally transmittedlocalization signals.
 2. The method as in claim 1, wherein the sensingtime window and/or the reference time are within the time period of atransmission period of the work cycle during which the data frame istransmitted, or within the time period of an idle period of the workcycle during which the in-vivo device refrains from transmitting data.3. The method as in claim 1, wherein measuring the time elapsing fromthe reference time comprises counting clock pulses of the clock signal,by a clock counter, relative to an initial count value.
 4. The method asin claim 3, comprising resetting the clock counter during each workcycle or during selected work cycles.
 5. The method as in claim 3,comprising initializing the clock counter to an initial value at a timeoverlapping with the reference time.
 6. The method as in claim 3,wherein the one or more localization signals are generated by theexternal localization signals source based on the restored clock signaland based on restored data indicative of the reference time.
 7. Themethod as in claim 1, wherein the data indicative of the reference timeis any one of: prefix data of the data frame, suffix data of the dataframe, data indicative of start-of-transmission of the data frame, dataindicative of end-of-transmission of the data frame, a group of databits in the data frame, and a data bit in the data frame.
 8. The methodas in claim 1, comprising: entering a sensing mode when a first timeelapses from the reference time, to enable sensing the one or moreexternally transmitted localization signals during the sensing timewindow; and exiting the sensing mode when a second time elapses relativeto the reference time.
 9. The method as in claim 8, wherein measuringtime specifics of the sensing time window and sensing time sub-windowscomprises counting clock pulses of the clock signal.
 10. The method asin claim 8, further comprising adjusting the time specifics contingenton a rate at which data frames are transmitted, to adjust the sensingtime window or the sensing time sub-window.
 11. The method as in claim1, wherein each localization signal is associated with a particularcoordinate of a coordinate system.
 12. The method as in claim 1, whereinthe sensing time window comprises one or more sensing time sub-windowsto facilitate sensing one or more localization signals respectivelyassociated with one or more coordinates, and comprising measuring timespecifics of the sensing time window and time specifics of each of thesensing time sub-windows relative to the reference time.
 13. The methodas in claim 12, wherein adjusting the time specifics comprises adjustinga number of clock pulses of the clock signal relative to the referencetime.
 14. The method as in claim 13, further comprising transmitting theadjusted number of cycles of the localization signal to the externallocalization signals source.
 15. The method as in claim 12, furthercomprising transmitting the adjusted time specifics to the in-vivodevice or to the receiver.
 16. The method as in claim 12, comprisingadjusting any one of a number of cycles of a localization signal and afrequency of a localization signal in response to an adjustment of thesensing time window or sensing time sub-window.
 17. An in-vivo devicecapable of timing sensing of externally generated localization signals,comprising: a timing mechanism having a clock generator to generate aclock signal to time a work cycle of the in-vivo device, within the workcycle is defined a reference time; a transmitter to transmit, within thework cycle, a data frame to a receiver, the data frame comprising datafacilitating restoration, by the receiver, of the clock signal and thereference time; a memory for storing time specifics of a sensing timewindow defined within the work cycle; a sensing coils assembly to senseexternally generated localization signals; a controller operably coupledto the timing mechanism, transmitter, memory and sensing coils assembly,wherein the controller is configured, within the work cycle, to: measuretime elapsing from the reference time by using the clock signal, and,based on the elapsed time and time specifics, operate the sensing coilsassembly to sense an externally generated localization signal during atime period overlapping with the sensing time window; and transmit,using the transmitter, data representative of the sensed externallygenerated localization signal.
 18. The in-vivo device as in claim 17,wherein the controller is further configured to change the timespecifics contingent on a rate at which the controller is transmittingdata frames using the transmitter.
 19. A data recorder for synchronizingbetween an in-vivo device and a localization system, the data recordercomprising: a memory for storing time specifics, the time specificsdefining a sensing time window within a work cycle of an in-vivo deviceduring which the in-vivo device operates a sensing coils assembly tosense one or more localization signals; a receiving unit to receive adata frame from the in-vivo device, the data frame comprising a clocksignal and a reference time originating from the in-vivo device; a timerestoration unit configured to use one or more data bits in the dataframe, to restore the clock signal and reference time from the receiveddata frame; and a synchronization signal generator operationally coupledto the receiving unit and time restoration unit, and configured tocause, based on the restored clock signal, restored time reference, andstored time specifics of the sensing time window, an externallocalization signals source to generate a localization signal during atime period overlapping with the sensing time window, for sensing theexternally generated localization signal by the in-vivo device duringthe sensing time window.
 20. The data recorder receiver as in claim 19,wherein the time specifics are adjustable contingent on a rate at whichthe receiving unit receives data frames from the in-vivo device, toadjust the sensing time window.